Earth and Planetary Science Letters最新文献

{"title":"Thin basaltic regolith at the Chang'e-6 landing site","authors":"Sheng Gou ,&nbsp;Zongyu Yue ,&nbsp;Yangting Lin ,&nbsp;Kaichang Di ,&nbsp;Patrick C. Pinet ,&nbsp;Wei Yang ,&nbsp;Yuyang He ,&nbsp;Yi Chen ,&nbsp;Roberto Bugiolacchi ,&nbsp;Hengci Tian ,&nbsp;Honglei Lin ,&nbsp;Sen Hu","doi":"10.1016/j.epsl.2025.119266","DOIUrl":"10.1016/j.epsl.2025.119266","url":null,"abstract":"<div><div>The Chang'e-6 (CE6) mission is the first probe that has returned samples from the lunar farside. The sampling site is located on the southern mare basalt within the Apollo peak-ring impact basin. The Apollo basin itself lies within the clearly-recognized, largest and oldest South Pole–Aitken (SPA) basin on the Moon. Samples from the SPA are believed to be of great implications for multiple critical lunar science questions, such as impact chronology, impact basin formation processes, as well as stratigraphy and composition of lunar lower crust/upper mantle. Using available data sets from previous lunar missions, this study proposes a subsurface stratigraphy for the CE6 landing area based on crater morphologies and their excavation depths. The result revealed the thickness of the basaltic regolith at CE6 landing site is as thin as ∼1.6 m. Compositional data suggested the basalt-dominant samples (Mg#: ∼40) actually contain both intermediate-Ti (∼5.6 wt.% TiO₂) and low-Ti (∼3.3 wt.% TiO₂) basalts, with exotic Mg-suite clasts (Mg#: ∼70) as ejecta mainly from craters inside the Apollo basin. The remotely sensed compositional signatures indicated that the CE6 probe had sampled KREEP (an acronym for potassium, rare earth elements, and phosphorus)-poor (Th: ∼2 ppm) high-Al (∼14 wt. % Al₂O₃) materials. Since the mare basalts were products of thermal evolution and partial melting of the mantle, they are appropriate agents to study lunar farside thermal and geochemical evolution, and examine the nearside-farside crustal and volcanic dichotomies. Given that the sampling site is located in the margin of the proposed SPA transient cavity and melt pool, the exotic Mg-suite clasts in the CE6 samples may represent shallower crustal materials, which have the potential to provide valuable insights into lunar crustal composition and stratigraphy.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119266"},"PeriodicalIF":4.8,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The relationship between gravity anomalies and topography in the Pacific Ocean and its implications for flexural isostasy, mantle viscosity and dynamics","authors":"An Yang ,&nbsp;A.B. Watts ,&nbsp;Shijie Zhong","doi":"10.1016/j.epsl.2025.119246","DOIUrl":"10.1016/j.epsl.2025.119246","url":null,"abstract":"<div><div>Mantle dynamics in the interior and flexural isostasy of the lithosphere contribute to Earth's topography and gravity fields at different wavelengths, yet the actual transition wavelength between mantle dynamics and flexural isostasy and their relative contribution are not well quantified. A critical parameter in determining the transition is Earth's viscosity structure which controls both the response of the plates to loading and mantle flow models. Here, we present the first study to use the observed relationship between topography and the gravity anomaly (admittance) at wavelengths from ∼200 km to ∼5000 km in the Pacific Ocean to determine the nature of the transition and to constrain mantle viscosity based on combined plate flexure and mantle flow models. The Pacific Ocean, as well as global, data suggest a transition wavelength of ∼600 km such that flexural isostasy dominates at wavelengths shorter than ∼600 km, while mantle dynamics also contributes significantly to the topography and gravity for wavelengths longer than ∼600 km. Mantle flow models based on different seismic tomography models have been used to determine the main controls on the dynamic admittance at wavelengths between 600 and 5000 km for the Pacific. We find that the observed admittance is best explained by a temperature-dependent viscosity mantle and a weak asthenosphere. These results are used to separate the contributions of flexural isostasy and mantle dynamics at long wavelength and to examine their implications for the amplitude of dynamic topography in the Pacific Ocean.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119246"},"PeriodicalIF":4.8,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extremely depleted radiocarbon impact on estimation of Glacial North Pacific Intermediate Water ventilation","authors":"Anqi Wang ,&nbsp;Zhengquan Yao ,&nbsp;Zhi Dong ,&nbsp;Xuefa Shi ,&nbsp;Yanguang Liu ,&nbsp;Sergey Gorbarenko ,&nbsp;Jianjun Zou ,&nbsp;Fengdeng Shi ,&nbsp;Xun Gong ,&nbsp;Alexander Bosin ,&nbsp;Yuriy Vasilenko ,&nbsp;Kunshan Wang ,&nbsp;Yazhi Bai ,&nbsp;Yijun Ren ,&nbsp;Weibin Zhang ,&nbsp;Han Feng ,&nbsp;Xinqing Zou","doi":"10.1016/j.epsl.2025.119254","DOIUrl":"10.1016/j.epsl.2025.119254","url":null,"abstract":"<div><div>Reconstructing the ventilation history of intermediate-depth Pacific Ocean remains challenging due to the influence of geologic carbon release, which biases radiocarbon (¹⁴C) ventilation age estimates. These uncertainties complicate the interpretation of past North Pacific Intermediate Water (NPIW) dynamics and its responses to climate variability. Here, we investigate NPIW changes during the last glaciation and subsequent deglaciation by analyzing benthic and planktonic ¹⁴C age offsets (B-P ¹⁴C age offsets), along with stable oxygen (δ¹⁸O_bf) and carbon isotope (δ¹³C_bf) records of benthic foraminifera in a sediment core from the southwestern Okhotsk Sea. The results indicate that B-P ¹⁴C age offsets were more than ∼9000 yrs during the last glaciation, suggesting a significant release of ¹⁴C-free geologic carbon, likely sourced from mixed gas clathrates in the southwestern Okhotsk Sea. These highly depleted ¹⁴C values have, therefore, led to an overestimation of ¹⁴C ventilation ages for Glacial North Pacific Intermediate Water in both the Okhotsk Sea and the Northwest Pacific during the Last Glacial Maximum (LGM). A compilation of δ¹⁸O_bf records from the North Pacific suggests that intermediate water formed in both the Okhotsk and Bering Seas during the LGM, extending to depths of at least ∼1590 m and ∼1000 m, respectively. Compared to the LGM, enhanced intermediate water formation in the Bering Sea during Heinrich Stadial 1 played an important role in intensifying NPIW, effectively flushing ¹⁴C-free geologic carbon from the Okhotsk Sea. This process might lead to a more uniform ventilation pattern at intermediate depths between the Northwest and Northeast Pacific. This study advances our understanding of NPIW evolution and reconciles previous discrepancies in ventilation reconstructions between the Northwest and Northeast Pacific during the LGM.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119254"},"PeriodicalIF":4.8,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Zirconium isotope evidence for crystal-melt segregation during high-silica granitic magma differentiation","authors":"Jionghui Wang ,&nbsp;Xi Zhang ,&nbsp;Zhaoxian Zhu ,&nbsp;Xinshui Wang ,&nbsp;Zaicong Wang ,&nbsp;Wen Zhang ,&nbsp;Fanghua Zhang ,&nbsp;Lanping Feng ,&nbsp;Shouhua Lai ,&nbsp;Qiushi Li ,&nbsp;Tao Luo ,&nbsp;Frédéric Moynier ,&nbsp;Zhaochu Hu ,&nbsp;Jing-Liang Guo","doi":"10.1016/j.epsl.2025.119251","DOIUrl":"10.1016/j.epsl.2025.119251","url":null,"abstract":"<div><div>Magma differentiation plays a crucial role in the chemical evolution of Earth's continental crust, with high-silica granites representing the product of extensive felsic magma differentiation. However, diagnostic evidence for crystal-melt segregation in felsic systems remains limited. This study investigates the potential of stable Zr isotopic composition as a novel tracer for high-silica magma differentiation processes, focusing on the Qitianling batholith and Yaogangxian pluton in the Nanling Range, South China, an area renowned for its large-scale distribution of high-silica granites (&gt;70 wt.% SiO₂). We present comprehensive analyses of both bulk-rock and in-situ zircon Zr isotopic compositions, integrated with zircon U-Pb-Hf isotopic and trace element data. Zircon Zr isotopic compositions show systematic correlations with zircon Hf contents and Zr/Hf ratios, demonstrating that Zr isotopic fractionation during zircon crystallization is driven by the preferential incorporation of light Zr isotopes in zircon. This relationship is further supported by correlations between bulk-rock δ^94/90Zr_IPGP values and Zr contents and Zr/Hf ratios, which indicate progressive zircon separation from residual melts during magmatic differentiation. As a result, highly fractionated granites display significant heavy Zr isotope enrichments, characterized by elevated δ^94/90Zr_IPGP values in both bulk rocks (0.48 ‰ to 1.05 ‰) and zircons (up to 2.39 ‰). In contrast, common granites with insignificant zircon-melt segregation display primitive bulk-rock Zr isotopic compositions (0.04 ‰ to 0.27 ‰) similar to the upper continental crust. These results indicate that effective physical crystal-melt segregation leads to a remarkable elevation in the bulk-rock and zircon δ^94/90Zr_IPGP values of highly fractionated granites compared to those of common granites. Geochemical modeling suggests that &gt;60 % segregation of zircon is required to account for the heavy Zr isotopic compositions in highly evolved granites. Furthermore, the high Zr isotopic values in zircon correlate with enriched U, W, Sn, and other incompatible elements, implying that Zr isotopic composition could serve as an indicator for mineralization potential associated with felsic magma differentiation.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119251"},"PeriodicalIF":4.8,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The inventory of OH and H2O in the non-polar regions of the Moon","authors":"Wen Yu ,&nbsp;Hao Yan ,&nbsp;Hong Tang ,&nbsp;Xiongyao Li ,&nbsp;Yu Wei ,&nbsp;Huiming Bao ,&nbsp;Chuanjiao Zhou ,&nbsp;Bing Mo ,&nbsp;Yanxue Wu ,&nbsp;Haiyang Luo ,&nbsp;Jialong Hao ,&nbsp;Ruiying Li ,&nbsp;Guangfei Wei ,&nbsp;Xiaojia Zeng ,&nbsp;Jianzhong Liu","doi":"10.1016/j.epsl.2025.119263","DOIUrl":"10.1016/j.epsl.2025.119263","url":null,"abstract":"<div><div>The image of a bone-dry surface in the Moon's non-polar regions impinged by the Apollo missions was changed by the detection of widespread absorption near 3 µm in 2009, interpreted as a signature of hydration. However, debates persist on the relative contribution of molecular water (H₂O) and other hydroxyl (OH) compounds to this hydration feature, as well as the cause of the potential temperature-dependence of the OH/H₂O abundance. Resolving these debates will help to estimate the inventory of water on the Moon, a crucial resource for future space explorations. In this study, we measured the abundance and isotope composition of hydrogen within the outermost micron of Chang'e-5 soil grains, collected from the lunar surface and from a depth of 1 m. These measurements, combined with our laboratory simulation experiments, demonstrate that solar-wind-induced OH can be thermally retained in lunar regolith, with an abundance of approximately 48–95 ppm H₂O equivalent. This abundance exhibits small latitude dependence and no diurnal variation. By integrating our results with published remote sensing data, we propose that a high amount of molecular water (∼360 ± 200 ppm H₂O) exists in the subsurface layer of the Moon's non-polar regions. The migration of this H₂O accounts for the observed latitude and diurnal variations in 3 µm band intensity. The inventory of OH and H₂O proposed in this study reconciles the seemingly conflicting observations from various instruments, including infrared/ultraviolet spectroscopies and the Neutral Mass Spectrometer (NMS). Our interpretation of the distribution and dynamics of lunar hydration offers new insights for future lunar research and space missions.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119263"},"PeriodicalIF":4.8,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Cenozoic intensification of deoxygenation in the Pacific Ocean","authors":"Katrina Nilsson-Kerr ,&nbsp;Babette A.A. Hoogakker ,&nbsp;Dharma A. Reyes Macaya ,&nbsp;Helge A. Winkelbauer ,&nbsp;Elliott Hamilton ,&nbsp;Simon Chenery ,&nbsp;Catherine V Davis ,&nbsp;Melanie J. Leng","doi":"10.1016/j.epsl.2025.119253","DOIUrl":"10.1016/j.epsl.2025.119253","url":null,"abstract":"<div><div>The Pacific Ocean hosts the largest expanse of oxygen depleted waters owing to a combination of factors influencing oxygen supply and consumption, with consequences for biogeochemical cycling. However, understanding of the long-term evolution of the Pacific Oxygen Deficient Zone remains poorly constrained. Here we apply the Iodine to Calcium (I/Ca) ratio in planktic foraminifera, in combination with the absence/presence of <em>Globorotaloides hexagonus</em>, from four tropical Pacific Ocean sites to reconstruct oceanic oxygen across the late Cenozoic. To validate the application of I/Ca, we supplement existing I/Ca calibration datasets by expanding their spatial coverage with additional core-top measurements. Our downcore results, combined with other lines of evidence, indicate the emergence and establishment of low oxygen waters from the late Miocene-Pliocene. The decline in Pacific Ocean oxygen accompanies large-scale climate and tectonic changes and likely impacted marine carbon cycling.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119253"},"PeriodicalIF":4.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transcrustal, volatile-charged silicic melts revealed by zircon-hosted melt inclusions","authors":"Damaris Butters ,&nbsp;Jon Blundy ,&nbsp;Brian Tattitch ,&nbsp;Chris Hawkesworth","doi":"10.1016/j.epsl.2025.119252","DOIUrl":"10.1016/j.epsl.2025.119252","url":null,"abstract":"<div><div>The volatile contents of silicic crustal magmas inform models for volcanism, crustal growth, degassing behaviour, and hydrothermal ore formation. Volatile saturation pressures of phenocryst-hosted melt inclusions are generally restricted to late-stage, shallow magmas that have undergone significant, ascent-driven degassing of H₂O, CO₂ and SO₂. As an alternative approach, we analyse the volatile contents of rhyolitic melt inclusions (10–30 µm diameter) in the accessory mineral zircon. We have developed a technique for the reheating of microcrystalline melt inclusions at elevated temperature (950 °C) and pressure (100 MPa) prior to analysis, to form homogeneous glassy inclusions without fracturing the host zircon. Analyses of volatiles were performed using secondary ion mass spectrometry and calculated volatile saturation pressures were used to obtain minimum melt inclusion trapping depths. Our results reveal that zircons often grow over an exceptional crustal depth range; many zircons trap melts deeper than 20 km. Significantly, the deepest melt inclusions from porphyry copper deposit-related magmas have high CO₂ contents (up to 4000 ppm), indicating CO₂-rich sources (fluid molar fraction of CO₂ up to 0.95). Zircon crystallisation and the trapping of melt inclusions testify to silicic melt generation over the entire crustal depth range. Deep crustal zircons can be transported to shallow levels by silicic melts percolating through transcrustal mush systems and/or in rapidly ascending volatile-charged magmas.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119252"},"PeriodicalIF":4.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance of North Indian geoid ridge and its implication to collision evolution between India and Eurasia","authors":"Peilong Yan ,&nbsp;Nan Zhang ,&nbsp;Xi Liu ,&nbsp;Bo Wan","doi":"10.1016/j.epsl.2025.119248","DOIUrl":"10.1016/j.epsl.2025.119248","url":null,"abstract":"<div><div>The geoid minima in the Indian Ocean and Siberia are separated by the North Indian Geoid Ridge (NIGR), yet the origin of the NIGR remains inadequately understood. Spherical harmonic analysis and geoid kernels indicate that the NIGR has wavelengths of degrees 7–10 and is mainly driven by density anomalies of similar degrees within the mantle. By employing numerical geoid modelling with four different tomography-derived density structures, we determined that abundant high-density anomalies in the mantle transition zone beneath North India and the Himalayas are responsible for the NIGR. Additionally, two contrasting tectonic evolutions of the India-Tibet collision, namely subduction roll-back scenario through the collision vs. lithospheric dripping scenario through the collision, are evaluated through geoid calculation. The former scenario suggests abundant high-density structures in the transition zone, capable of generating a well-constrained NIGR, while the latter does not support this. Consequently, we consider the Indian lithosphere subduction roll-back to be the more plausible evolving scenario.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119248"},"PeriodicalIF":4.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lower crustal thickening drives active uplift in Northern Tibet","authors":"Shaozhuo Liu ,&nbsp;Xiwei Xu ,&nbsp;Jean-Mathieu Nocquet ,&nbsp;Guihua Chen ,&nbsp;Xibin Tan ,&nbsp;Sigurjón Jónsson ,&nbsp;Yann Klinger","doi":"10.1016/j.epsl.2025.119245","DOIUrl":"10.1016/j.epsl.2025.119245","url":null,"abstract":"<div><div>Mountains in collisional orogens generally grow as crustal rocks are advected over low-angle thrust faults, suggesting a close relationship between tectonic uplift and upper crustal shortening. For example, the Himalayas, hosting large-scale thrust fault systems, undergoes ∼15–20 mm/year shortening and concomitant ∼5 mm/year active uplift. However, geodetic observations reveal an active uplift of 1–2 mm/year across the East Kunlun Shan mountain range, the northern margin of the Tibetan Plateau, where no active thrust fault has been identified. This active uplift is too fast to be explained by the limited horizontal shortening of at most 1.0 ± 0.2 mm/year. After quantifying and correcting for contributions arising from erosion, (de)glaciation, and recent earthquakes, the uplift rate across the East Kunlun Shan still amounts to 1.0 ± 0.5 mm/year. Our simulations show that mantle processes cannot explain the GPS-observed uplift. We find that lower crustal thickening, rather than upper crustal shortening alone, drives the ongoing uplift across the East Kunlun Shan, hence challenging our current views on mountain range dynamics.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"655 ","pages":"Article 119245"},"PeriodicalIF":4.8,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MgO miscibility in liquid iron","authors":"Leslie Insixiengmay ,&nbsp;Lars Stixrude","doi":"10.1016/j.epsl.2025.119242","DOIUrl":"10.1016/j.epsl.2025.119242","url":null,"abstract":"<div><div>We explore phase equilibria on the MgO-Fe join as a prototype of lithophile-core interaction in terrestrial planets. Our density functional theory simulations are based on a phase coexistence method: fluids of initially pure MgO and Fe compositions are allowed to establish a dynamic equilibrium across a near-planar interface. Methods for analyzing the composition and other properties of the two coexisting phases show that MgO behaves as a component, with indistinguishable Mg and O concentrations in Fe-rich and oxide-rich phases. The phase diagram is well described as that of a symmetric regular solution, a picture confirmed by independent one-phase determinations of the enthalpy, entropy, and volume of mixing. The critical temperature, above which there is complete miscibility across the MgO-Fe join is 7000 K at 68 GPa, and 9000 K and 172 GPa. The rate of MgO exsolution from the Fe-rich liquid on cooling is similar to that found in previous experimental studies, and is too small to drive a dynamo.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"654 ","pages":"Article 119242"},"PeriodicalIF":4.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143300330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}